Optical device

Abstract

The present invention provides a highly-integrated and compact optical element and further provides an optical element having various functions such as lower driving voltage, chirping suppression and polarization-independency. The optical element has a substrate 1 formed of a material having an electrooptic effect, a plurality of optical waveguides formed on the substrate, and a modulating electrode for applying electric field into the optical waveguides, and is characterized in that the modulating electrode has at least two branching and confluence lines on the same line for applying the same modulating signal into different optical waveguides.

1. An optical element comprising
 a substrate formed of a material having an electrooptic effect, 
 a plurality of optical waveguides formed on said substrate, and 
 a modulating electrode for applying electric field into said optical waveguides, wherein said modulating electrode comprises at least two branching and confluence lines on a same line for applying a same modulating signal into different optical waveguides, and 
 wherein one portion of said optical waveguides is turned back at a side edge of said substrate, and the branching and confluence lines on the same line are respectively positioned at least before and behind said turnback of optical waveguide. 
 
   
   
     2. The optical element according to  claim 1 , wherein said optical waveguides comprise a plurality of Mach-Zehnder type optical waveguides being connected in series, and a plurality of branching and confluence lines on a same line are located corresponding to each of said Mach-Zehnder type optical waveguides. 
   
   
     3. The optical element according to  claim 1 , wherein a ferroelectric spontaneous polarization of one part of said substrate comprising the optical waveguides, into which electric field is applied by said branching and confluence lines, is reversed. 
   
   
     4. The optical element according to  claim 2 , wherein a ferroelectric spontaneous polarization of one part of said substrate comprising the optical waveguides, into which electric field is applied by said branching and confluence lines, is reversed. 
   
   
     5. The optical element according to  claim 1 , wherein at least one of said branching and confluence lines has one or more delay lines between a branching point and a confluence point. 
   
   
     6. The optical element according to  claim 2 , wherein at least one of said branching and confluence lines has one or more delay lines between a branching point and a confluence point. 
   
   
     7. The optical element according to  claim 3 , wherein a middle line between said branching and confluence lines has a delay line. 
   
   
     8. The optical element according to  claim 4 , wherein a middle line between said branching and confluence lines has a delay line. 
   
   
     9. The optical element according to  claim 5 , wherein a middle line between said branching and confluence lines has a delay line. 
   
   
     10. The optical element according to  claim 6 , wherein a middle line between said branching and confluence lines has a delay line. 
   
   
     11. An optical element comprising
 a substrate formed of a material having an electrooptic effect, 
 a plurality of optical waveguides formed on said substrate, and 
 a modulating electrode for applying electric field into said optical waveguides, wherein said modulating electrode comprises at least two branching and confluence lines on a same line for applying a same modulating signal into different optical waveguides, and 
 wherein said optical waveguides comprise a plurality of Mach-Zehnder type optical waveguides being connected in series, and a plurality of branching and confluence lines on a same line are located corresponding to each of said Mach-Zehnder type optical waveguides. 
 
   
   
     12. The optical element according to  claim 11 , wherein a ferroelectric spontaneous polarization of one part of said substrate comprising the optical waveguides, into which electric field is applied by said branching and confluence lines, is reversed. 
   
   
     13. The optical element according to  claim 11 , wherein at least one of said branching and confluence lines has one or more delay lines between a branching point and a confluence point. 
   
   
     14. The optical element according to  claim 12 , wherein a middle line between said branching and confluence lines has a delay line. 
   
   
     15. The optical element according to  claim 13 , wherein a middle line between said branching and confluence lines has a delay line.